| A strain producing protease was isolated from soil of Shaoguan city, by determining hydrolytic zone inmilk plate media. The strain was identified as Serratia marcescens, according to morphologic observation,physiological tests, biochemical tests, and 16S rDNA sequence alignment. The fermentation broth of the ms2 straincontained alkaline protease, because the optimum reactive pH of proteases was 10.0. The proteases had maximalactivity at 45, and remained beyond 70% activity for 100 min at 45. The proteases activities were improved byMn2 +, but were inhibited by Cu2 + and Fe2 +. Their activities were strongly inhibited by EDTA, but not by -mercaptoethanol. So the results indicated that the fermentation both had some kind metallo protease. Compared withAlcalase protease, the proteases showed higher hydrolysis activity to soy isolate protein. In single factor tests, whenthe nitrogen sources and the carbon sources individually were casein and sucrose, the fermentation broth had thehighest protease activity. |
